. the assistant curator at the aquarium of the bay in san francisco told us shark sightings are common in the bay area this time of year. in fact, the large seven-gill shark on display at the aquarium was caught last month near alcatraz. but he says shark attacks on humans are rare. >> obviously, there have been documented cases of shark attacks. but again, at the same time there are also statistics that will say you're more likely to be struck by lightning than you are to be, you know, bitten by a shark. >> reporter: experts also say many varieties of sharks visit the northern california coast. particularly between august and december. >> it's not uncommon for them to come into the bay, particularly right underneath the golden gate bridge into the mouth of the bay. they will come in there to feed off sea lions. >> reporter: and experts admit there have been more sightings of great white sharks this summer than usual. they say that should be a reminder to anyone who goes into the water this labor day weekend to be careful. live in pacifica tonight, monte francis, nbc bay area news. >> all right.